JPH0343784B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a resin composition for semiconductor encapsulation that has good fluidity during molding, has less burrs, and has less mold wear. In recent years, transfer molding has become the mainstream for encapsulating semiconductor devices due to its excellent mass production and economic efficiency.However, with the expansion of applicable devices and the pursuit of high reliability, the characteristics required for molding resins have also become more important. It's getting tougher. In particular, it is desired to improve the degree of integration of ICs, increase the chip size, and improve resins for power-up. One type of sealing material that meets these required characteristics is one that uses both fused silica, which has a low coefficient of thermal expansion, and crystalline silica, which has high thermal conductivity, as fillers, that is, contains both of the above silicas in an epoxy resin, etc. It is known that This type of sealing material reduces thermal strain on the chip, suppressing chip cracks and resin cracks, and also efficiently dissipates heat generated from the chip to the outside, suppressing the temperature rise of the chip. The reliability of semiconductors can be greatly improved. However, in the case of sealing materials using such mixed silica, fluidity during molding may not be sufficient, or on the contrary, it may flow too much, making it easy for burrs to occur, and mold wear may be significant. In some cases, the process was not always satisfactory in terms of molding workability. As a result of intensive investigation into the causes of the above, the inventors found that the above-mentioned problems were mainly caused by the particle sizes of the fusible silica powder and crystalline silica powder used, and found that the particles By setting the diameter within a specific range and specifying the mixing ratio of both silicas and the content of mixed silica in the entire composition, good results can be obtained in terms of fluidity, burrs, and mold wear. This led to the completion of this invention. That is, this invention provides (A) fusible silica powder with a particle size of 46μ or more and 30% by weight or more, 149μ or more and 1% by weight or less, and (B) a fusible silica powder with a particle size of 46μ or more and 1% by weight or less, and 10μ
A resin composition for semiconductor encapsulation characterized by comprising 60% by weight or more of crystalline silica powder and 60 to 85% by weight of filler powder having an A/(A+B) of 0.3 to 0.7. It is something. To explain in detail the particle size of the two silica powders used in this invention, first, the particle size is 46 μm.
By using fusible silica powder with a particle size of 30% or more and by using crystalline silica powder with a particle size of 46μ or more and 1% by weight or less, that is, by using fusible silica powder with a coarse particle size. , the effect of reducing mold wear can be obtained. In addition, the above-mentioned crystalline silica powder with a reduced particle size has a particle size of 10μ or less and 60% by weight or more, which gives good results to the bounce characteristics of the particle size of the entire mixed powder and improves fluidity. Both the burr characteristics and the burr characteristics are satisfied. In addition, the particle size of fusible silica is 149μ
By setting the content to 1% by weight or less, clogging of the gate during molding can be prevented. In this invention, A/(A+B), that is, the ratio of fusible silica to the total amount of fusible silica powder and crystalline silica powder, is set to 0.3 to 0.7. This is because both characteristics can be satisfied. That is, when the above ratio is less than 0.3, fluidity decreases, and conversely, when the above ratio is greater than 0.7, burrs are likely to occur. The proportion of mixed silica consisting of fusible silica powder and crystalline silica powder in the entire composition is 60 to 60%.
It should be 85% by weight; if it is less than 60% by weight, the coefficient of thermal expansion will be too large and the thermal conductivity will be poor, and if it is more than 85% by weight, the fluidity will be extremely poor or the resin will not enter the cavity. The wraparound becomes poor and moldability is impaired. The above-mentioned silicas used in this invention need to be of high purity. For example, when 1 g of silica is boiled with 10 g of pure water, the electrical conductivity of the extract is
Desirably, the content is 10μν/cm or less, Na is 5ppm or less, and Cl is 5ppm or less. The resin content used in this invention is as follows:
Although a wide variety of thermosetting resins are included, epoxy resins such as phenol novolac type epoxy resins, cresol novolak type epoxy resins, bisphenol A type epoxy resins, and alicyclic type epoxy resins are particularly suitable. Furthermore, known curing agents such as phenolic resins, amines, acid anhydrides, and isocyanates can be used without particular limitation. The resin composition for semiconductor encapsulation of the present invention may contain other additives such as colorants, flame retardants, mold release agents, coupling agents, curing accelerators, etc. within the scope of the purpose of the present invention. . In particular, in order to speed up the curing properties, it is preferable to mix one or more of imidazoles, imidazolines, tertiary amines, etc. as curing accelerators. The kneading or mixing in preparing the resin composition for semiconductor encapsulation of the present invention may be performed by melt-kneading using heated rolls, melt-kneading using a pot, melt-kneading using an extruder, or any combination thereof. Next, examples of this invention will be described. Example Epoxy equivalent: 220, 16 parts of cresol novolak epoxy resin with a softening point of 75°C, epoxy equivalent: 275,
2.5 parts of flame-retardant epoxy resin with a softening point of 79°C, hydroxyl equivalent 105, 8.0 parts of phenol novolac resin with a softening point of 76°C, 0.4 parts of 2-methylimidazole, 0.3 parts of carnauba wax, 0.5 parts of silane coupling agent,
1.8 parts of antimony trioxide and 0.3 parts of carbon book
In addition, silica powder having the particle size shown in Table 1 was used in the composition ratio (parts by weight) shown in Table 2, and 8 types of semiconductor encapsulation including comparative examples were performed using the following method. A resin composition for use was produced. That is, first, the filler and antimony trioxide are mixed with a coupling agent, then the remaining materials are added, further pulverized and mixed, and then kneaded for 10 minutes with a mixing roll heated to 80°C, and then shaped into a sheet. I made it. This was cooled and pulverized to obtain a resin composition powder for semiconductor encapsulation.

[Table] The spiral flow of the obtained resin composition powder was measured according to EMMI-I-66 as a guideline for fluidity. To find out how burrs appear,
Transfer molding was performed (175°C, 5 minutes) using a mold with a 5μ gap, and the length of burrs coming out of the gap was evaluated. In order to investigate the abrasion resistance of the mold, the degree of wear of the gate portion after molding using a non-quenched mold was evaluated. These results were as shown in Table 2 below.

[Table] As is clear from the above results, the resin composition for semiconductor encapsulation of the present invention has excellent characteristics in that it satisfies both fluidity and burr properties and has low mold abrasion. This shows that it is possible to provide an industrially useful resin composition that can take advantage of the inherent characteristics of thermal expansion coefficient and thermal conductivity due to the combined use of fused silica and crystalline silica.

Claims (1)

[Scope of Claims] 1 (A) Fusible silica powder with a particle size of 46μ or more and 30% by weight or more, 149μ or more and 1% by weight or less, and (B) a particle size of 46μ or more and 1% by weight or less and 10μ or less and 60% by weight or more filler powder consisting of crystalline silica powder and having A/(A+B) of 0.3 to 0.7.
A resin composition for semiconductor encapsulation characterized by containing 60 to 85% by weight.